Storing carbon dioxide under the German North Sea is possible
To achieve the climate targets, the German government approved the underground storage of carbon dioxide. A research association is exploring the North Sea.
Norwegian CCS plant Sleipner
(Image: Equinor)
Where to put the carbon dioxide? Storing the greenhouse gas under the North Sea is possible in principle. But only in limited quantities. The possibility of storage does not exempt us from reducing emissions. This is the conclusion of the first interim report of the research association on CO2 storage in sandstone formations under the German North Sea (GEOSTOR).
The research association, which is coordinated by the GEOMAR Helmholtz Center for Ocean Research Kiel, has investigated the nature of the North Sea floor to determine whether it is suitable for storing the gas. The researchers have identified two areas that could be suitable. One is the West Schleswig Block around 100 kilometers off the coast, the other, much smaller, is in the so-called Entenschnabel, the northwesternmost tip of the German Exclusive Economic Zone.
(Image: Rita Erven, CDRmare, GEOMAR)
According to the interim report, the West Schleswig Block is “geologically speaking, probably the most promising area for CO2 storage”. The West Schleswig Block is a domed red sandstone formation covered by a barrier rock. Between 900 and 550 million tons of carbon dioxide could be stored there.
Transport by ship and through a pipeline
Up to 10 million tons of carbon dioxide could be transported to the storage sites each year, the researchers write. The transportation is to take place by tank wagon to the coast. There, the carbon dioxide would first be loaded onto ships and transported to the injection site. Later, a pipeline will be built through which the carbon dioxide will be pumped to the storage site.
“The main challenges currently lie in taking precautions to prevent leaks from the storage rock,” explained GEOSTOR coordinator Klaus Wallmann. It is also important to reduce noise during reservoir exploration and monitoring to disturb marine wildlife as little as possible, as well as to find solutions for conflicts of use, for example with offshore wind farms, and to take these into account in marine spatial planning.
Finally, the team also looked at the costs. According to the study, the transfer of one ton of carbon dioxide to the West Schleswig block would cost between 26 and 55 euros in the initial phase. This includes the investment and operating costs for the hub, seaborne transportation and storage. Once the infrastructure is ready, the costs will fall to between 13 and 28 euros per tonne. Transport to a storage facility in the Duckbill would be three to ten euros more expensive per tonne due to the greater distance.
Carbon dioxide capture is expensive
However, these costs only relate to transportation to the storage site and storage. The costs for carbon dioxide capture and onshore transportation have not been considered, which could turn out to be quite high, according to the report.
Germany wants to become climate-neutral by 2045. To achieve this, the German government approved the underground storage of carbon dioxide at the beginning of 2024. Without carbon capture and storage (CCS) or carbon capture and utilization (CCU) of carbon dioxide, Germany's climate targets would be impossible to achieve, said Federal Economics Minister Robert Habeck (Greens) at the time.
However, the GEOSTOR report emphasizes that only limited storage capacities are available in the German North Sea. “Due to the limited capacities and possible environmental risks, however, only the residual amount of CO2 that cannot be avoided despite consistent climate policy should be deposited there.”
(wpl)